i. Technical Field
This invention pertains generally to the field of web-slitting machines in which a large supply roll of web-like material, such as paper, is longitudinally slit into a plurality of narrower webs, with the narrower webs being subsequently rewound. More particularly, the invention pertains to an apparatus for effecting the change from a first set of cores or winding tubes having fully wound rolls thereon to a second set of empty cores for receiving the slit web.
ii. Prior Art
Two types of rewinding arrangements for web-slitting machines have been used widely in the past. In the first type, a support roller is present, and the roll cores, which are held by clamping pins of support arms, are disposed in contact with the support roller, at least at the beginning of coiling. The clamping pins are driven, to continuously rotate the cores during the rewinding process. Viewed in the longitudinal direction of the support roller, the cores for sequential narrow webs are positioned alternately in the right and left upper quadrants of the support roller.
The second type of rewinding arrangement commonly used for web-slitting machines is composed of two parallel support rollers placed at the same height, and winding takes place at the outer upper quadrant of each support roller. Clamping pins and support arms similar to those described previously are used to hold and rotate the roll cores. Again, viewed in the longitudinal direction of the support roller, the cores for sequential narrow webs are positioned alternately at the first and second support roller.
As the diameter of the rolls being formed begins to enlarge during the wind-up process in either of the afore-described arrangements, if the roll builds up under continuous contact with the support roller, the contact point with the support roller is essentially retained. However, it is also possible to wind up freely; i.e, after beginning the coiling, the roll being formed is lifted off the support roller by a small amount so that a free-running length of the narrow web running from the support roller to the roll being wound remains.
In either the single drum or double drum winder, it is important that the adjacent narrow rolls are formed alternately in first and second sets of winding stations as described. The reason for this is that the individual narrow webs are not significantly separated or displaced transversely to the web running direction; but at the same time, the narrow rolls being wound are held by support arms which protrude outwardly at the narrow roll ends, thus taking up space. If adjacent, narrow, partial webs are wound directly side-by-side, insufficient space is provided for the support arms. For this reason, adjacent narrow webs must be separated for rewinding in different sets of winding stations.
State-of-the-art web-slitting machines possess considerable winding speeds. Indeed, the working speed, i.e., the total time needed for processing a wide roll, e.g., a roll of paper machine width coming from the paper machine, into the appropriate number of narrow rolls, is significantly determined by the length of down time during which empty roll cores are being installed, the cores are tightened and connected to the ends of the partial webs, the webs are removed from the finished narrow rolls and the finished, wound, narrow rolls are removed from the web-slitting machine. Often, on web-slitting machines of this type, the cores are installed by hand and are glued or stapled to the ends of the narrow, partial webs. This work includes the danger of operating accidents, and, like all manual processes, it is time-consuming.
The present invention is based on the need to increase the working speed of web-slitting machines.